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Advances in Marine Engineering: Geological Environment and Hazards
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Advances in Marine Engineering: Geological Environment and Hazards

A special issue of Journal of Marine Science and Engineering (ISSN 2077-1312). This special issue belongs to the section "Geological Oceanography".

Deadline for manuscript submissions: closed (31 October 2022) | Viewed by 25023

Printed Edition Available!
A printed edition of this Special Issue is available here.

Special Issue Editors

Prof. Dr. Xiaolei Liu

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Guest Editor
Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering, College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100, China
Interests: marine engineering geology; wave-seabed interactions; submarine sediment gravity flows; seafloor in-situ test and observation
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Thorsten Stoesser

E-Mail Website
Guest Editor
Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 6BT, UK
Interests: computational fluid dynamics; coastal hydraulics and environmental fluid mechanics
Special Issues, Collections and Topics in MDPI journals
Dr. Xingsen Guo

E-Mail Website
Guest Editor
Department of Civil, Environmental and Geomatic Engineering, University College London, London WC1E 6BT, UK
Interests: marine geotechnical engineering; marine geological disasters; marine engineering geology and environment; deep-sea mining; hydrodynamics; non-Newtonian fluid; two-phase flows; LES; CFD; turbidity current; gravity flow; fluid-structure interaction; sediment plume; pipes and piles
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

With the continuous advancement of coastal, offshore, and deep-sea engineering construction (e.g., marine resource development, offshore wind power projects, etc.), research on marine geological environments and hazards have gradually deepened and many research advances have been achieved. Therefore, this Special Issue has been organized by Prof. Xiaolei Liu, Prof. Thorsten Stoesser, and Dr. Xingsen Guo to document these research advances. The objective of this Special Issue is to collect research papers in the field of marine geological environments and hazards, including geological environments, geological hazards, engineering geology, hydrodynamics, fluid environments, and geotechnical engineering. This Special Issue invites contributions on in situ observations, indoor tests, numerical simulations, and theoretical analysis on marine geological environments and hazards. Contributions may also include case studies, review articles, or short communications.

Prof. Dr. Xiaolei Liu
Prof. Dr. Thorsten Stoesser
Dr. Xingsen Guo
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Journal of Marine Science and Engineering is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • marine geological environment
  • marine geological hazards
  • marine engineering geology
  • marine hydrodynamics
  • marine environment fluid
  • marine geotechnical engineering

Published Papers (15 papers)

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Editorial

Jump to: Research, Review

5 pages, 190 KiB  
Editorial
Advances in Marine Engineering: Geological Environment and Hazards
by Xingsen Guo, Xiaolei Liu and Thorsten Stoesser
J. Mar. Sci. Eng. 2023, 11(3), 475; https://doi.org/10.3390/jmse11030475 - 22 Feb 2023
Viewed by 1356
Abstract
With the continuous advancement of coastal, offshore, and deep-sea engineering construction (e [...] Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)

Research

Jump to: Editorial, Review

13 pages, 7479 KiB  
Article
Development and Testing of a High-Resolution Three-Dimensional Seismic Detection System for Gas Hydrate
by Chenguang Liu, Qingxian Zhao, Zhen Liu, Yanhong Lian, Yanliang Pei, Baohua Liu, Xishuang Li, Qingjie Zhou, Keping Yan and Zili Chen
J. Mar. Sci. Eng. 2023, 11(1), 20; https://doi.org/10.3390/jmse11010020 - 23 Dec 2022
Cited by 1 | Viewed by 1377
Abstract
As a novel type of mineral resource, gas hydrate has received a considerable amount of attention worldwide. This seismic detection method can detect abnormal phenomena such as the BSR, blank zones, velocity anomalies and polarity inversion of gas hydrate and become an important [...] Read more.
As a novel type of mineral resource, gas hydrate has received a considerable amount of attention worldwide. This seismic detection method can detect abnormal phenomena such as the BSR, blank zones, velocity anomalies and polarity inversion of gas hydrate and become an important method of gas hydrate detection. The occurrence area of gas hydrate in the South China Sea is usually buried deep beneath the seabed. The current method cannot meet the needs of the shape and structure detection of gas hydrate deposits. With the support of the National Key R&D Program of China, some key technologies have led to developmental breakthroughs, such as ultra-high-energy plasma sources, small-group-interval high-resolution seismic streamers, and distributed three-dimensional seismic acquisition. The seismic profile obtained north of the South China Sea shows that the stratum penetration depth reaches nearly 1000 m at a depth of 1500 m, and the vertical resolution is better than 1.5 m. This system can serve the needs of high-resolution exploration of gas hydrate resources. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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17 pages, 2255 KiB  
Article
Analytical Solutions of Steady a Seepage Field for Deep-Buried Tunnel with Grouting Ring Considering Anisotropic Flow
by Qizhi Chen, Luju Liang, Baoping Zou, Changjie Xu, Bowen Kong and Jingyuan Ma
J. Mar. Sci. Eng. 2022, 10(12), 1861; https://doi.org/10.3390/jmse10121861 - 02 Dec 2022
Cited by 6 | Viewed by 1241
Abstract
Difficulties related to seepage are frequently encountered in tunnel design and construction, especially in deep-buried tunnels. Nowadays, analytical solutions of steady seepage fields for deep-buried tunnel usually assume that the surrounding rock mass is homogeneous. In this study, analytical solutions of a steady [...] Read more.
Difficulties related to seepage are frequently encountered in tunnel design and construction, especially in deep-buried tunnels. Nowadays, analytical solutions of steady seepage fields for deep-buried tunnel usually assume that the surrounding rock mass is homogeneous. In this study, analytical solutions of a steady seepage field for a deep-buried tunnel with grouting ring considering anisotropic flow are proposed. The proposed analytical solutions are verified by numerical simulations and parameter analysis are carried out. Results show that the seepage field of surrounding rocks around the deep buried circular tunnel is no longer uniformly distributed and presents elliptical distribution. The change of permeability coefficient of the lining structure has a great influence on the hydraulic head when the difference between permeability coefficient of lining structure and surrounding rock is not very large. The results show that the size of the grouting ring has more significant influence on the grouting effect. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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15 pages, 4715 KiB  
Article
Experimental Study on Dynamic Parameters of Calcareous Sand Subgrade under Long-Term Cyclic Loading
by Ziyu Wang and Lei Zhang
J. Mar. Sci. Eng. 2022, 10(12), 1806; https://doi.org/10.3390/jmse10121806 - 22 Nov 2022
Cited by 5 | Viewed by 1325
Abstract
A long-term cyclic loading test of calcareous sand from an island reef in the South China Sea was conducted under conditions of unequal consolidation and drainage. The axial cumulative strain and dynamic characteristics of coral sand samples with different physical and mechanical properties [...] Read more.
A long-term cyclic loading test of calcareous sand from an island reef in the South China Sea was conducted under conditions of unequal consolidation and drainage. The axial cumulative strain and dynamic characteristics of coral sand samples with different physical and mechanical properties were studied under different stress levels, yielding a model prediction formula. The results show that (1) the axial cumulative strain and dynamic elastic modulus increase with increasing vibration times of the cyclic load, whereas the dynamic damping ratio decreases with increasing cyclic vibration time; (2) the axial cumulative strain, elastic modulus, and damping ratio are affected by dynamic stress amplitude, load frequency, confining pressure, consolidation stress, compactness and moisture content; and (3) based on dynamic triaxial test results, the axial cumulative strain model of calcareous sand under cyclic loading and its permanent deformation prediction formula are established by introducing the cyclic stress ratio. Two parameters, the elastic modulus evolution parameter and the damping ratio evolution parameter, are introduced, and the axial cumulative strain is normalized. The results of this research have significance for understanding the long-term deformation and dynamic response of coral sand subgrade soil under cyclic vibration loads. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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17 pages, 5515 KiB  
Article
Analysis of Cyclic Shear Stress–Displacement Mechanical Properties of Silt–Steel Interface in the Yellow River Delta
by Peng Yu, Jie Dong, Haisong Liu, Rui Xu, Rujie Wang, Meijun Xu and Hongjun Liu
J. Mar. Sci. Eng. 2022, 10(11), 1704; https://doi.org/10.3390/jmse10111704 - 09 Nov 2022
Cited by 7 | Viewed by 1102
Abstract
Pile foundations of offshore structures are often subjected to cyclic loads under storm loads, thus reducing their vertical bearing capacity. Therefore, studying the cyclic shear behavior of the soil–structure interface is important for maintaining the stability of offshore structures. A series of cyclic [...] Read more.
Pile foundations of offshore structures are often subjected to cyclic loads under storm loads, thus reducing their vertical bearing capacity. Therefore, studying the cyclic shear behavior of the soil–structure interface is important for maintaining the stability of offshore structures. A series of cyclic shear tests of the silt–steel interface were carried out using a large interface shear apparatus. The effects of various factors (i.e., normal stress, shear displacement amplitude, roughness, and water content) on the shear stress characteristics of the silt–steel interface were investigated. The stress–displacement model of the cyclic shear silt–steel interface was deduced. The results showed that the shear stress at the silt–steel interface was softened, and the type of bulk deformation was shear shrinkage under cyclic shear. With the increase in shear amplitude, the hysteresis curve gradually developed from “parallelogram” to “shuttle” and “hysteresis cake”. With the increase in normal stress and roughness and the decrease in water content, the interfacial shear strength, volume displacements growth rate, and growth rate increased. The stress–displacement mathematical model of the silt–steel interface based on the modified hyperbolic model was in good agreement with the test data. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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24 pages, 9983 KiB  
Article
Nonlinear Predictive Framework of the Undrained Clay Slope Effect on the Initial Stiffness of p-y Curves of Laterally Loaded Piles by FEM
by Li Pang, Chong Jiang and Lujie Chen
J. Mar. Sci. Eng. 2022, 10(11), 1684; https://doi.org/10.3390/jmse10111684 - 07 Nov 2022
Cited by 3 | Viewed by 1001
Abstract
The hyperbolic p-y curve method is commonly used to design laterally loaded piles, in which the initial stiffness is one of the two key parameters that need to be determined. In this paper, the effect of an undrained clay slope on the initial [...] Read more.
The hyperbolic p-y curve method is commonly used to design laterally loaded piles, in which the initial stiffness is one of the two key parameters that need to be determined. In this paper, the effect of an undrained clay slope on the initial stiffness of p-y curves of laterally loaded piles was explored, and nonlinear models of the reduction factor (μ) were proposed. A series of finite-element analyses was performed for different pile–slope geometric relationships according to whether the slope geometry had influence on pile–soil interaction, in which the geometrical parameters were varied. Based on simulation results, a semi-empirical method was mainly used to derive nonlinear formulations for the undrained clay slope effect on the initial stiffness of hyperbolic p-y curves. The wedge failure theory was also used to analyze the effect of the dimensionless slope height on the initial stiffness. Comparing with other researchers’ reduction factor models, the results of the present model are in the reasonable range and can predict more cases. Test cases were used to validate the proposed model, and the results show that theoretical results are in better agreement with test results using the present model. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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11 pages, 2891 KiB  
Article
Sediment Waves on the Western Slope of the Chukchi Rise (Arctic Ocean) and Their Implications for the Paleoenvironment
by Qingfeng Hua, Guanbao Li, Qingjie Zhou, Shujiang Li, Tengfei Xu, Baohua Liu and Hongxia Chen
J. Mar. Sci. Eng. 2022, 10(11), 1586; https://doi.org/10.3390/jmse10111586 - 26 Oct 2022
Cited by 1 | Viewed by 1602
Abstract
Based on multibeam bathymetric data and high-resolution shallow sub-bottom profiles acquired during China’s 10th Arctic Scientific Expedition Cruise in 2019, a sediment wave field was found on the western slope of the Chukchi Rise, in the Arctic Ocean. This sediment wave field developed [...] Read more.
Based on multibeam bathymetric data and high-resolution shallow sub-bottom profiles acquired during China’s 10th Arctic Scientific Expedition Cruise in 2019, a sediment wave field was found on the western slope of the Chukchi Rise, in the Arctic Ocean. This sediment wave field developed on the lower slope with water depths of between 1200 m and 1800 m and stretched 15 km in the downslope direction. It comprised several parallel sediment waves, with wavelengths ranging from 700 m to 3400 m and wave heights from 12 m to 70 m. In the vertical direction, well-stratified deposits, tens of meters thick, were affected by sediment waves, which exhibit asymmetric waveforms and upslope migration trends. The morphological and seismostratigraphic characteristics of the sediment waves suggested their genesis as a result of the interaction between the bottom current and seafloor morphology, which was also supported by hydrographical data adjacent to the sediment wave field. It was infered that this bottom current was related to the Arctic Circumpolar Boundary Current, which many researchers suggest flows through the study area. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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16 pages, 8994 KiB  
Article
Effect of Low Temperature on the Undrained Shear Strength of Deep-Sea Clay by Mini-Ball Penetration Tests
by Zhongde Gu, Xingsen Guo, Houbin Jiao, Yonggang Jia and Tingkai Nian
J. Mar. Sci. Eng. 2022, 10(10), 1424; https://doi.org/10.3390/jmse10101424 - 03 Oct 2022
Cited by 4 | Viewed by 1545
Abstract
The technology for in situ testing of the undrained shear strength of deep-sea clay is underdeveloped. Indoor tests remain necessary, and there is a large temperature difference between in situ and laboratory tests. To analyse the effect of temperature on undrained shear strength, [...] Read more.
The technology for in situ testing of the undrained shear strength of deep-sea clay is underdeveloped. Indoor tests remain necessary, and there is a large temperature difference between in situ and laboratory tests. To analyse the effect of temperature on undrained shear strength, in this study the physical characteristics of marine clay samples from the South China Sea were determined, followed by penetration tests by the mini-ball method under low (4 °C) and room (20 °C) temperatures. The results indicated that the clay strength increased by 14.1–30.0% as the temperature decreased from 20 °C to 4 °C, and the strength of the bound water and the viscosity of the free water in the clay sample increased as the temperature decreased, which was the root cause of the increase in the clay strength. Based on the research, it is possible to correct the undrained shear strength values measured in laboratory tests and provide more reasonable parameters for ocean engineering. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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20 pages, 4602 KiB  
Article
Origin and Implications of Pollution in Coastal Groundwater of the Guangdong Province
by Chenzhe Li, Tengfei Fu, Yushan Fu, Zhenyan Wang, Bin Li, Chen Qi, Guangquan Chen, Xingyong Xu and Hongjun Yu
J. Mar. Sci. Eng. 2022, 10(10), 1394; https://doi.org/10.3390/jmse10101394 - 29 Sep 2022
Cited by 4 | Viewed by 1598
Abstract
The groundwater resource is crucial to the urbanization and industrialization in the Guangdong coastal area; the rapid development of Daya Bay has presented a challenge for the management of the groundwater quantity and quality. Therefore, a novel approach to hydrochemical analysis, which, combined [...] Read more.
The groundwater resource is crucial to the urbanization and industrialization in the Guangdong coastal area; the rapid development of Daya Bay has presented a challenge for the management of the groundwater quantity and quality. Therefore, a novel approach to hydrochemical analysis, which, combined with the health risk model and the water quality index (WQI), was used to explain the hydrochemistry characteristics and risks to human health of groundwater in the Guangdong coastal areas in addition to investigating the factors controlling groundwater quality. The results showed that the average concentration of total dissolved solids (TDS) in groundwater was 1935.26 mg/L and the quality of water was weakly alkaline. The dominant hydrochemical types of groundwater were identified to be Mg-HCO3 and Na-Cl·HCO3. The main factor influencing the hydrochemical composition was rock weathering, while the result of principal component analysis (PCA) shows seawater intrusion and anthropogenic inputs also have an effect on the water quality. The conclusions of the water quality assessment indicated that most of the groundwater samples were acceptable for drinking. However, both WQI and the non-carcinogenic hazard quotient (HQ) values indicated unacceptable risks in any area of Maoming, Zhanjiang and Shantou, and, according to the hazard index (HI) value, children in the study area are at more danger to health risks than adults. It is suggested that both groundwater salinization and nitrate pollution should be paid attention to when improving groundwater quality and exploring the sustainable utilization of groundwater resources. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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15 pages, 3489 KiB  
Article
Predicting the Sound Speed of Seafloor Sediments in the East China Sea Based on an XGBoost Algorithm
by Mujun Chen, Xiangmei Meng, Guangming Kan, Jingqiang Wang, Guanbao Li, Baohua Liu, Chenguang Liu, Yanguang Liu, Yuanxu Liu and Junjie Lu
J. Mar. Sci. Eng. 2022, 10(10), 1366; https://doi.org/10.3390/jmse10101366 - 24 Sep 2022
Cited by 5 | Viewed by 1342
Abstract
Based on the acoustic and physical data of typical seafloor sediment samples collected in the East China Sea, this study on the super parameter selection and contribution of the characteristic factors of the machine learning model for predicting the sound speed of seafloor [...] Read more.
Based on the acoustic and physical data of typical seafloor sediment samples collected in the East China Sea, this study on the super parameter selection and contribution of the characteristic factors of the machine learning model for predicting the sound speed of seafloor sediments was conducted using the eXtreme gradient boosting (XGBoost) algorithm. An XGBoost model for predicting the sound speed of seafloor sediments was established based on five physical parameters: density (ρ), water content (w), void ratio (e), sand content (S), and average grain size (Mz). The results demonstrated that the model had the highest accuracy when n_estimator was 75 and max_depth was 5. The model training goodness of fit (R2) was as high as 0.92, and the mean absolute error and mean absolute percent error of the model prediction were 7.99 m/s and 0.51%, respectively. The results demonstrated that, in the study area, the XGBoost prediction method for the sound speed of seafloor sediments was superior to the traditional single- and two-parameter regressional equation prediction methods, with higher prediction accuracy, thus providing a new approach to predict the sound speed of seafloor sediments. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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12 pages, 2076 KiB  
Article
High-Frequency Dependence of Acoustic Properties of Three Typical Sediments in the South China Sea
by Jingqiang Wang, Zhengyu Hou, Guanbao Li, Guangming Kan, Baohua Liu, Xiangmei Meng, Qingfeng Hua and Lei Sun
J. Mar. Sci. Eng. 2022, 10(9), 1295; https://doi.org/10.3390/jmse10091295 - 14 Sep 2022
Cited by 4 | Viewed by 1457
Abstract
The acoustic characteristics of three fine-grained sediments (silty sand, silt, silty clay) in the South China Sea (SCS) were measured and analyzed at high frequency range of 27–247 kHz. The measurement results show that the sound speed dispersion is a positive linear relation [...] Read more.
The acoustic characteristics of three fine-grained sediments (silty sand, silt, silty clay) in the South China Sea (SCS) were measured and analyzed at high frequency range of 27–247 kHz. The measurement results show that the sound speed dispersion is a positive linear relation at the measured frequency range, and the attenuation follows nonlinear frequency dependence, α = kfn, where n ranges from 0.59 to 0.85 for the three different sediments in the SCS. The frequency dependence of sound speed and attenuation were compared with the published literature. It was found that for silty clay, clayey silt, silt, and silty sand, the dispersion characteristics of these four sediments are basically consistent; in general, the dispersion of coarse particles is significant, and that of fine particles is weak, and permeability is the key parameter that determines the inflection point of high frequency to low frequency. By modeling these sediments with the Biot–Stoll model, it was found that the Biot–Stoll model can better predict the frequency-dependent characteristics of sound attenuation in a high-frequency band under the matching constraints of sound speed dispersion characteristics, indicating that the Biot–Stoll model has good applicability to different types of sediments in a high-frequency band. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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16 pages, 3924 KiB  
Article
Study on the Rheology of CO2 Hydrate Slurry by Using the Capillary Method
by Weiqi Fu, Wei Wei, Hao Wang, Bingxiang Huang and Zhiyuan Wang
J. Mar. Sci. Eng. 2022, 10(9), 1224; https://doi.org/10.3390/jmse10091224 - 01 Sep 2022
Cited by 8 | Viewed by 1272
Abstract
The rheological properties of the CO2 hydrate slurry are experimentally investigated by using a new flow loop with an inner diameter of 50 mm. The pressure drops of the CO2 hydrate slurry are measured experimentally under the volumetric hydrate fraction, ranging [...] Read more.
The rheological properties of the CO2 hydrate slurry are experimentally investigated by using a new flow loop with an inner diameter of 50 mm. The pressure drops of the CO2 hydrate slurry are measured experimentally under the volumetric hydrate fraction, ranging from 1.4 to 17.2 vol%, and the shear rate ranging from 40 to 590 s−1. Using the capillary method, the rheology of the CO2 hydrate slurry is analyzed based on pressure drop. The CO2 hydrate slurry is identified as a power-law fluid and exhibits strong shear-thickening behavior. The increase in the volumetric hydrate concentration not only ascends the apparent viscosity, but also makes the non-Newtonian behavior of the hydrate slurry become more obvious. The non-Newtonian index and the consistence factor of fluid increase exponentially with the volumetric hydrate concentration increasing. A Herschel–Bulkley-type rheological model of the CO2 hydrate slurry is correlated from experimental data. The developed model performs the average discrepancy of less than 16.3% within the range of the experiment. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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15 pages, 5155 KiB  
Article
Normalized Stress–Strain Behavior of Deep-Sea Soft Soils in the Northern South China Sea
by Ying Yang, Hailei Kou, Zhenghui Li, Yonggang Jia and Chaoqi Zhu
J. Mar. Sci. Eng. 2022, 10(8), 1142; https://doi.org/10.3390/jmse10081142 - 18 Aug 2022
Cited by 5 | Viewed by 1725
Abstract
The study of the physical and mechanical properties of marine soil is of great importance for marine geohazard prediction, submarine energy extraction, and submarine foundation design. In this study, a series of basic geotechnical tests and triaxial compression tests are performed on samples [...] Read more.
The study of the physical and mechanical properties of marine soil is of great importance for marine geohazard prediction, submarine energy extraction, and submarine foundation design. In this study, a series of basic geotechnical tests and triaxial compression tests are performed on samples taken from the Shenhu sea area in the South China Sea (SCS). Physical and mechanical properties, particularly normalized stress–strain behavior, are investigated. The microstructural and mineralogical characterization is carried out, through scanning electron microscopy (SEM), and X-ray diffraction (XRD). The results indicated that the sample could be classified as high-plasticity silt (MH) with high water content and high compressibility, that the soil has the highest quartz content in its mineral composition, a loose skeleton composed of flocculent structures under the microscope and is distributed with the remains of marine organisms. Furthermore, a new stress–strain-normalized condition is theoretically derived, based on the hyperbola function. In this condition, the concept of standard normalized factor, which is defined as the ultimate value of principal stress difference, is introduced. Meanwhile, the normalized stress–strain relationship of soft soil from the SCS is established under consolidated undrained conditions and the results of the model are compared with the experimental results, with a good normalization effect. It is believed that the work presented in this paper could contribute to the design and construction of offshore engineering. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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23 pages, 9202 KiB  
Article
Discrete Element Simulation of the Macro-Meso Mechanical Behaviors of Gas-Hydrate-Bearing Sediments under Dynamic Loading
by Yujing Jiang, Meng Li, Hengjie Luan, Yichen Shi, Sunhao Zhang, Peng Yan and Baocheng Li
J. Mar. Sci. Eng. 2022, 10(8), 1042; https://doi.org/10.3390/jmse10081042 - 29 Jul 2022
Cited by 7 | Viewed by 1549
Abstract
Under the action of dynamic loadings such as earthquakes and volcanic activities, the mechanical properties of gas-hydrate-bearing sediments will deteriorate, leading to a decrease in the stability of hydrate reservoirs and even inducing geological disasters such as submarine landslides. In order to study [...] Read more.
Under the action of dynamic loadings such as earthquakes and volcanic activities, the mechanical properties of gas-hydrate-bearing sediments will deteriorate, leading to a decrease in the stability of hydrate reservoirs and even inducing geological disasters such as submarine landslides. In order to study the effect of dynamic loading on the mechanical properties of hydrate sediments, triaxial compression tests of numerical specimens were carried out by using particle flow code (PFC2D), and the macro-meso mechanical behaviors of specimens were investigated. The results show that the loading frequency has a small effect on the stiffness of the hydrate sediment, while it has a large effect on the peak strength. The peak strength increases and then decreases with the increase in loading frequency. Under the same loading frequency, the peak strength of the hydrate sediment increases with the increase in loading amplitude, and the stiffness of the specimen decreases with the increase in loading amplitude. The maximum shear expansion of the specimen changes with the movement of the phase change point and the rearrangement of the particles. The maximum shear expansion of the specimen changes with the movement of the phase change point and the change of the bearing capacity of the particles after the rearrangement, and the more forward the phase change point is, the stronger the bearing capacity of the specimen in the plastic stage. The shear dilatancy angle and the shear dilatancy amount both increase linearly with the increase in loading amplitude. The influence of loading frequency and amplitude on the contact force chain, displacement, crack expansion, and the number of cementation damage inside the sediment is mainly related to the average axial stress to which the specimen is subjected, and the number of cracks and cementation damage of the sediment specimen increases with the increase in the average axial stress to which the sediment specimen is subjected. As the rate of cementation damage increases, the distribution of shear zones becomes more obvious. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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Review

Jump to: Editorial, Research

16 pages, 2827 KiB  
Review
Recent Technological and Methodological Advances for the Investigation of Submarine Landslides
by Zhigang Shan, Hao Wu, Weida Ni, Miaojun Sun, Kuanjun Wang, Liuyuan Zhao, Yihuai Lou, An Liu, Wei Xie, Xing Zheng and Xingsen Guo
J. Mar. Sci. Eng. 2022, 10(11), 1728; https://doi.org/10.3390/jmse10111728 - 11 Nov 2022
Cited by 14 | Viewed by 3405
Abstract
Submarine landslides have attracted widespread attention, with the continuous development of ocean engineering. Due to the recent developments of in-situ investigation and modelling techniques of submarine landslides, significant improvements were achieved in the evolution studies on submarine landslides. The general characteristics of typical [...] Read more.
Submarine landslides have attracted widespread attention, with the continuous development of ocean engineering. Due to the recent developments of in-situ investigation and modelling techniques of submarine landslides, significant improvements were achieved in the evolution studies on submarine landslides. The general characteristics of typical submarine landslides in the world are analyzed. Based on this, three stages of submarine landslide disaster evolution are proposed, namely, the submarine slope instability evolution stage, the large deformation landslide movement stage, and the stage of submarine landslide deposition. Given these three stages, the evolution process of submarine landslide disaster is revealed from the perspectives of in-situ investigation techniques, physical simulation, and numerical simulation methods, respectively. For long-term investigation of submarine landslides, an in-situ monitoring system with long-term service and multi-parameter collaborative observation deserves to be developed. The mechanism of submarine landslide evolution and the early warning factors need to be further studied by physical modelling experiments. The whole process of the numerical simulation of submarine landslides, from seabed instability to large deformation sliding to the impact on marine structures, and economizing the computational costs of models by advanced techniques such as parallel processing and GPU-accelerators, are the key development directions in numerical simulation. The current research deficiencies and future development directions in the subject of submarine landslides are proposed to provide a useful reference for the prediction and early warning of submarine landslide disasters. Full article
(This article belongs to the Special Issue Advances in Marine Engineering: Geological Environment and Hazards)
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